------- Comment #8 from jv244 at cam dot ac dot uk 2008-11-11 06:00 ------- (In reply to comment #7) > Actually we can fold C - a == a only for odd C. > But more generally a +- b == a to b == 0. > right... that works as well for this optimization.
The original argument was on the range of a and thus C-a. Which allows also folding C - a == a for non-odd values of C. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31029
